Stretchable resistive fabrics or elastomers as strain gauges are known in the art. Touch sensors implemented with conducting materials are also known in the art. In these applications, electrostatic discharge (ESD) protection of the electronics input stage is established generally by a resistor in series with each of the capacitive sensor traces.
It is also known that touch sensors are generally implemented on solid state or stiff substrates and are generally not wearable. Strain gauges are implemented always on stretchable substrates due to the nature dictated by the function of a strain gauge.
US2016018274 discloses a textile pressure sensor comprising knit metal stitches and designed to be elastic both in the longitudinal direction and in the transverse direction. The knitted fabrics of the textile pressure sensor configure a first and a second structure that are conductive at least in regions thereof. An intermediate isolating element is arranged between the first and the second conductive structures. Both the surface and the capacitance of this textile pressure sensor are not constant due to the fact that the textile structure can be extended in the various directions. This can lead to errors in the pressure measurement. Accordingly, the effects of these extensions have to be compensated for example through an extension measurement.
In particular, the above-mentioned document describes the use of an array of strain gauges to measure the amount of elongation of the textile fabric to compensate for the capacity variation which in turn affects the calculated pressure.
However, the main aim of the above prior art textile pressure sensor is to measure pressure or, more precisely, pressure distribution along the fabric by using capacitance between electrodes as the phenomenon to indirectly measure pressure.
US2015294756 discloses a flexible pressure detection platform comprising at least one layer of insulating material sandwiched between a first electrode layer and a second electrode layer, each electrode layer comprising an array of strip electrodes embedded in a flexible material. Pressure is measured based on capacitance change at the intersection of specific vertical and horizontal conductive stripes.
US20160048235 describes interactive textiles. The interactives textiles include a grid of conductive thread woven into the interactive textile to forma a capacitive touch sensor that is configured to detect touch input. Detected touch inputs can be used to control remote devices.